Passenger conveyors such as escalators and moving walkways are provided with constantly tensioned components which are designed to ensure proper operation despite stretching thereof which will occur over extended periods of time. Examples of such tensioned components are the step chain, and the handrail drive. The step chains are reeved over sprockets which are positioned beneath each of the conveyor landings. One of the sprocket sets is connected to the drive motor and provides the drive power for moving the step chains and steps. This powered sprocket set is usually located at the upper landing in an escalator. The other sprocket set is an idler sprocket which simply reverses the direction of movement of the step chains and steps. The idler sprocket is typically mounted on a carriage which is translationally movable relative to the step chain, which carriage serves as a step chain tensioning carriage. The carriage is biased by springs so as to apply a continuous tension to the step chain loops. Thus, as the step chains stretch after time, the tension imparted to them will not diminish and the step chains will not slacken. Since the step chain tension is constant, due to the use of the springs, the chains will remain under tension even when the conveyor is not in operation, as for example, during overnight periods, and between factory assembly and installation of the escalator, or walkway in the field. The maintenance of step chain tension during extended periods of non-use is not desirable. The step chain rollers and the step trailer rollers are formed with elastomeric rolling surfaces which reduce vibration and noise during conveyor operation. When the conveyor is shut down for extended periods of time, the elastomeric surfaces of the step rollers will develop localized flat spots on them where the rollers are pressed against the guide tracks. These flat spots will cause operating noise and vibration, and thus are undesirable. The conveyor step chain can be de-tensioned between assembly and installation, but there is no presently available equipment for de-tensioning the step chain during temporary, but relatively extended non-operating periods; and there is no presently available equipment for automatically retensioning the step chain when the escalator is to be put into service.
In addition to the step chain, the handrail drive assembly is another component of the conveyor that would benefit from detensioning during extended periods of non-operation. Escalator and moving walkway handrails are moved over guide tracks by a drive system which exerts a compressive force on the handrail. The handrail-engaging portion of the drive system may include elastomeric rollers which engage the handrail; or a drive belt that engages the handrail. The driving portion will be pretensioned so as to apply a predetermined pressure to the handrail. When the conveyor is shut down for extended periods of time, as noted above, the drive member may develop flat spots, and the area of the handrail contacted by the drive member will also develop localized flat spots or indentations. As noted above, the localized flat spots or depressions in the drive system or handrail will result in noise generation and uneven operation. The aforesaid problems with passenger conveyor operation can be curtailed if the tensioned drive components are detensioned or relaxed during non-operating periods of time, or "down time."